import { isMobile } from './is';

const flexible = async (window: Window, document: Document) => {
  const docEl = document.documentElement;
  const dpr = window.devicePixelRatio || 1;

  // adjust body font size
  function setBodyFontSize() {
    if (document.body) {
      document.body.style.fontSize = 16 * dpr + 'px';
    } else {
      document.addEventListener('DOMContentLoaded', setBodyFontSize);
    }
  }
  setBodyFontSize();

  // 移动端 set 1rem = viewWidth / 10
  // pc网页 set 1rem = viewWidth / 24
  function setRemUnit() {
    const numberOfCopies = isMobile() ? 10 : 24;
    const rem = docEl.clientWidth / numberOfCopies;
    console.log('rem', rem);
    console.log('%O', docEl, 'docEl.clientWidth');
    console.log(docEl.clientWidth, 'docEl.clientWidth');
    docEl.style.fontSize = rem + 'px';
  }

  const docElFontSize = docEl.style.fontSize;
  if (!docElFontSize) {
    setRemUnit();
  }
  // reset rem unit on page resize
  window.addEventListener('resize', setRemUnit);
  window.addEventListener('pageshow', function (e) {
    if (e.persisted) {
      setRemUnit();
    }
  });

  // detect 0.5px supports
  if (dpr >= 2) {
    const fakeBody = document.createElement('body');
    const testElement = document.createElement('div');
    testElement.style.border = '.5px solid transparent';
    fakeBody.appendChild(testElement);
    docEl.appendChild(fakeBody);
    if (testElement.offsetHeight === 1) {
      docEl.classList.add('hairlines');
    }
    docEl.removeChild(fakeBody);
  }
};

export default flexible;
